فحوصات

• What is one indication for performing a liver CT scan?

  Suspected focal or diffuse liver lesion
• What is another indication for a liver CT scan?

  Staging known primary or secondary malignancy
• What abnormal test result might indicate the need for a liver CT scan?

  Abnormal liver-function tests
• What symptom might prompt a liver CT scan?

  Right upper-quadrant pain or mass
• What is a physical finding that could indicate the need for a liver CT scan?

  Hepatomegaly
• What condition might be suspected that would require a liver CT scan?

  Suspected portal hypertension
• What is another reason for performing a liver CT scan?

  Characterization of liver lesion
• What is a less common indication for a liver CT scan?

  Pyrexia of unknown origin
• Why might a liver CT scan be performed to assist with a procedure?

  To facilitate the placement of needles for biopsy
• What vascular structures might be assessed during a liver CT scan?

  Assessment of portal vein, hepatic artery or hepatic veins
• What is one indication for a liver CT scan related to surgical procedures?

  Assessment of patients with surgical shunts or TIPS procedures
• What is a follow-up reason for performing a liver CT scan?

  Follow-up after surgical resection or liver transplant
• What is a contraindication for performing a liver CT scan?

  Pregnancy
• What is another contraindication for a liver CT scan?

  Allergy to iodinated contrast agents
• What is the technique used for the majority of routine liver CT imaging?

  Single-phase (portal phase) contrast-enhanced computed tomography
• When is the liver imaged during a single-phase CT scan?

  During the peak of parenchymal enhancement
• How long after the start of a bolus injection is the liver imaged?

  Around 60-70 seconds
• Is oral contrast necessary for liver CT imaging?

  No, it is not necessary if only the liver is being investigated
• What is the recommended slice thickness for liver CT scans?

  5 mm or less
• What are the phases of contrast-enhanced computed tomography for liver imaging?

  • Arterial phase: Begins 20-25 seconds after bolus injection
  • Early arterial phase: 25 seconds after bolus injection
  • Late arterial phase: 35 seconds after bolus injection
  • Portal venous phase: 60-70 seconds after bolus injection
  • Delayed phase: 180 seconds after bolus injection (optional)
• Why do liver tumors enhance differently than normal hepatic parenchyma?

  Liver tumors receive their blood supply from the hepatic artery
• What happens to hypervascular tumors during the arterial phase?

  They enhance strongly
• What is the significance of washout in liver imaging?

  It indicates that tumors may be of similar or lower density to normal parenchyma
• What is the purpose of a triple phase scan in liver imaging?

  To investigate suspected hepatocellular cancer
• What is the purpose of a quadruple phase scan?

  To help identify and characterize primary liver tumors
• What is a characteristic enhancement pattern of haemangiomas?

  Peripheral discontinuous nodular enhancement and progressive centripetal 'fill-in'
• What is the technique used for computed tomographic cholangiography?

  Opacification of the biliary tree using an intravenous cholangiographic agent
• What is the slice thickness for multidetector CT cholangiography?

  0.625 mm section thickness slices
• What is a contraindication for computed tomographic cholangiography?

  Allergy to iodinated contrast agents
• What is one indication for performing computed tomographic cholangiography?

  Screening for cholelithiasis (stones)
• What is the technique for computed tomography of the pancreas?

  Negative oral contrast is generally preferred
• What is the volume of intravenous contrast typically used for pancreatic CT?

  100 to 150 mL
• What is the timing for pancreatic parenchymal phase enhancement?

  35-40 seconds after commencement of bolus injection
• What is the purpose of portal venous phase scans in pancreatic CT?

  To investigate hepatic metastatic disease
• What is the slice thickness for images reconstructed in the pancreatic phase?

  0.625-1.25 mm
• How do islet cell tumors appear on arterial phase scans?

  They may show avid enhancement
• Why is a portal phase scan generally necessary for islet cell tumors?

  To investigate flow and the relationship of the tumor to the portal vein